N/A
The present invention relates generally to air cooling of electronic devices, and more specifically to forced air cooling of such devices by multiple fans mounted in a tray coupled to a chassis.
Cooling of electronic devices is typically accomplished by way of ambient or forced convection cooling. When forced convection cooling is used, a volume of air is directed past the electronic devices either by suction or by pressure. In the chassis for such devices, it is known to mount components on cards and to orient the cards parallel to the direction of air flow to enhance cooling.
When a single fan is used to supply the forced convection cooling, the electronic devices are liable to be damaged should the fan fail; or, if fan failure is detectable, the system may be subject to unscheduled shutdown to prevent such damage. In addition, as the volume of air required to cool the devices increases, the audible noise of a powerful fan moving larger volumes of air may preclude the system from being installed in an office or a residence.
When multiple fans are used, the failure of a single fan may not cause damage but reduces the volume of air being provided for cooling. A failed fan may degrade the performance of the fan system because the failed fan acts like an opening in the chassis allowing some of the forced air to escape without cooling the electronic devices.
It would therefore be desirable to have a fan tray for cooling electronic devices. Such a fan tray would be easily coupleable to a chassis, would provide sufficient air cooling to electronic devices even if one of a plurality of fans incorporated therein fails to operate, and would be relatively quiet during fan operation. It would also be desirable to have a fan tray that reduces air diversion from the cooling airflow and minimizes the need for blocking structures in the area to be cooled.
In accordance with the present invention, a fan tray is provided that includes a number of fans laid out in an array to draw air through the tray. Such a tray is adapted to be incorporated in a variety of chassis where cooling of electronic devices is needed. In one aspect, the fan tray is mounted below an electronics enclosure drawing in ambient air. The fan tray incorporates interlocks that require that all power and signal connections to the fan tray be disconnected before the tray can be removed. The fan tray can operate with or without a filter installed beneath the fan tray. However, if the filter is installed, the filter cannot be removed without disconnecting power to the tray prior to removal.
An air dam separates a one rank of fans from another rank. The dam improves upward airflow and decreases air diversion should one fan fail. The air dam further creates a plenum allowing air pressure to build and laminar airflow to develop before entering the card cage. The plenum may be made more effective by extended its depth. While the increased depth may be accomplished by deepening the fan tray, it can also be accomplished by creating a plenum under the enclosure. When the fan tray is mounted beneath the enclosure, the two plenums may be aligned forming one extended plenum. A baffle in the enclosure plenum, aligned with the air dam, further improves the operation of the assembly. The plenum arrangement further allows increased airflow from operational fans to compensate for a failed fan.
Multiple fans supply the same airflow as one larger fan with the benefits of quieter and more reliable operation even if one of the fans fails.